Wavelength extension and power improvement of red Pr³⁺:YLF lasers

High-power red lasers (mainly at 639 and 670 nm) based on Pr³⁺:YLF crystals have been presented in many works. However, the spectral resources of Pr³⁺:YLF in the red region have not been fully developed to obtain lasers due to their relatively low emission cross sections and the irrepressible strong emission at ∼639 nm. In this work, we propose a scheme to further develop the spectral resources of Pr³⁺:YLF in the red region and improve the red laser powers based on this crystal. The laser wavelengths are obtained from 634.5 to 674.7 nm (continuous tunings are achieved at some wavebands). To the best of our knowledge, the output powers obtained at 638.7, 644.6, 670.1, and 674.7 nm (2.88 W, 1.87 W, 3.55 W, and 1.73 W, respectively) are the highest to date. Furthermore, lasing originating from the ³P₂ energy level of Pr³⁺:YLF (∼653 nm) is realized for the first time.